The Global Properties of MgII Absorption Systems at Redshift One
AAS meeting San Diego jan. 2005.
N. Milutinovic, J. C. Charlton, J. Ding (Penn State), C. W. Churchill (NMSU)

ABSTRACT:
 

Ultraviolet and optical quasar spectra provide coverage of multiple ionization states of many chemical transitions of the absorbing gaseous content of the Universe. A sample of 19 MgII absorption systems at redshifts 0.4 to 1.4 will be presented. This research surveys the gas in galaxies, as well as in gaseous clouds that produce metal absorption far from any luminous source. Photoionization and collisional ionization modeling was used to infer multiphase
properties of this systems including their metallicities, densities, and temperatures.

Combining these results, we seek overall trends and strive to find subcategories of MgII systems. We focus on several general issues:

i. Are the densities of the gas phases that produce MgII absorption similar or different among different MgII absorbers? This question is related to the global properties of interstellar medium gas at different locations and in galaxies with different morphological types;

ii. Is CIV gas in strong MgiI systems related to the presence or absence of galactic coronae, which are thought to be produced/maintained by star-forming processes in the disk? A CIV phase could be absent in some systems due to elliptical hosts, a low star formation rate, an outer disk line of sight, or a randomly sparse region;

iii. How common are high velocity clouds around $z \sim 1$ galaxies, and how do their properties differ from the Milky Way high velocity clouds?;

iv. What is the nature of multiple cloud weak MgII absorbers? Could they be related to dwarf galaxies, which despite a significant absorption cross section are hard to connect to other classes of absorption systems?

v. Are there cold phases of gas in absorption systems (DLAs and strong MgII
absorbers) that relate to HI regions/photodissociation regions/regions surrounding molecular clouds?
 

Housing Weak Mg II Absorbers In The Cosmic Web
AAS meeting Atlanta jan. 2004.
Nikola Milutinovic, Jane Charlton, Jie Ding, Joe Masiero, Chris Palma (Penn State University) and Jane Rigby (U. Arizona),
 

ABSTRACT:

We present an investigation of the geometry and morphology of weak MgII systems (Wr(2796)<0.3A). These absorbers trace abundant, metal-enriched regions (close to solar metallicity) that may lie in faint dwarf galaxies or in intergalactic space. Generally, models show that they have a ~10pc region of higher density gas and a ~1kpc region that represents a lower density phase of higher ionization absorption. We based our work on a search of 35 quasar spectra from the archive of high resolution, ultra-violet HST/STIS data. When possible, we supplemented these spectra with Keck/HIRES and HST/FOS data that cover more transitions over a larger range of wavelengths. When MgII is not covered we used other low ionization transitions, CII and SiII, to trace the MgII phase. In a comparison between absorption systems detected in low and/or high ionization gas (traced by CIV absorption), we found the following: 1. Almost all of weak MgII analog systems have an associated high ionization phase. In some cases the CIV has only a single component, kinematically centered on the low ionization absorption, and in other cases there are additional CIV components offset in velocity. There is one system in quasar 3c 273 without a high ionization cloud. 2. There are twice as many CIV-only systems as systems with both CIV and weak MgII analog absorption detected. 3. The CIV absorption in weak MgII systems is on average stronger than that in the CIV-only systems. 4. The CIV absorption in weak MgII systems has similar kinematic structure as that in the CIV-only systems. Based on these results and on physical properties of the different phases of the absorbers we consider possible geometries. We suggest that sheetlike geometries are favored, due to the relatively small cross-section of CIV-only systems.

Cosmological Constant And The Ly-alpha Forest Statistics
XIII National Conference Of Yugoslav Astronomers 2002
Nikola Milutinovic (PSC), Katarina Kovac, Milan M. Cirkovic (AOB)
 

ABSTRACT:

We investigate the impact of recent discovery of a large positive vacuum energy density ("cosmological constant") on our interpretation of the Ly-alpha forest cloud statistics. It has been known for some time that, contrary to the usual situation in cosmology, the impact of non-zero Lambda on the cloud population is larger in the low-redshift limit that in the high-redshift one. We show that this offers a significant circumstantial support to the theory that Ly-alpha clouds are gravitationally confined (in mini-haloes as well as large galactic haloes). 

 

- Nenad Bozinovic, Nikola Milutinovic, 2000, Polarization of White Light
Corona During The Total Eclipse 1999, Petnica papers, Science Center Petnica  ..... html (eng, serb)

- Nikola Milutinovic, Nenad Bozinovic, 1999, CCD Photometry of M74
Spiral Galaxy

- Nikola Milutinovic, 1997, Correlation Between Some Parameters of Active
Sensitive Lines And Sun Activity, Petnica papers, Science Center Petnica

- Nikola Milutinovic, 1996, Light Curve of Variables RR Lyr and TV Cas,
Petnica papers, Science Center Petnica